U.S. Pat. No. 3,896,131 describes a broad class of 6,7-dihydro-5-methyl-1-oxo-1H,5H-benzo[ij]quinolizine-2-carboxylic acids as antimicrobial agents. The patent specifically discloses several compounds substituted by halogen and/or methyl on the benzo ring. The compound 6,7-dihydro-9-fluoro-5-methyl-1-oxo-1H,5H-benzo[ij]-quinolizine-2-carboxyl ic acid (now known as flumequine) which is disclosed in the aforementioned patent has received the most attention for its antimicrobial activity. It has now been found that the corresponding novel 8-methyl-9-fluoro compound exhibits greatly enhanced antimicrobial activity.
U.S. Pat. No. 4,301,289 describes the compounds 6-fluoroquinaldine, 6-fluoro-1,2,3,4-tetrahydroquinaldine, and dialkyl 2-[N-(6-fluoro-1,2,3,4-tetrahydroquinaldinyl]- methylenemalonates.